"There is enormous equity in the wizarding world that now spans generations," says Warners' Sue Kroll of the high-stakes 'Harry Potter' spinoff.

At a carefully choreographed fan event for J.K. Rowling's Fantastic Beasts and Where to Find Them in mid-October, the old mixed with the new. Execs at Warner Bros., which threw the party and will release the film Nov. 18, delighted as Harry Potter fans dressed in traditional Hogwarts uniforms mingled with others adorned in the 1920s New York City garb of the new spinoff.

Warners has been walking this fine line in marketing Fantastic Beasts for more than two years in a bold gamble to win over fans of the Boy Who Lived and expand Rowling's Potterverse with a new film franchise based on a more adult cauldron of wizards. Further upping the stakes, the press-shy Rowling, who wrote the script, took the stage at the event to reveal there will be five Fantastic Beasts movies, even though the first film still was a month from opening.

If the $180 million movie works (and early reviews have been strong), Warners CEO Kevin Tsujihara can claim the biggest victory of his tenure amid an $85 billion bid by AT&T to buy parent company Time Warner. If not, the studio's decision to announce five films will be heavily scrutinized, along with whether all will actually get made.

It was Tsujihara who struck the deal with Rowling in 2013 for Fantastic Beasts, a prequel set 70 years before the events in Rowling's Harry Potter book series. The eight Potter movies earned $7.7 billion at the global box office for Warners (the second-most-successful franchise after the Marvel universe, not accounting for inflation), so the look and feel (including wisps of the original John Williams score) were employed in ads and trailers to make fans feel at home.

"There is enormous equity in the wizarding world that now spans generations," says Warners marketing and distribution president Sue Kroll. "We fashioned a campaign to resonate with that passionate fan base, introducing them [to Rowling's] completely new story and new characters while bringing along a new, uninitiated audience to Fantastic Beasts."

The studio has put Rowling front and center for many of its promotional efforts, including the Fantastic Beasts premieres in New York and London.

"She's the heart and soul of it," says producer David Heyman of Rowling. "Jo Rowling has no need to do this. Her need is her desire and her love of this world. The greatest security you can have is that Jo Rowling wanted to tell the story."

So far, Potterheads have been willing to embrace an expanded universe. The Wizarding World of Harry Potter theme park attractions in Los Angeles, Orlando and Japan have been a massive boost for Universal Parks and Resorts, which has a licensing deal with Warners. A West End play, Harry Potter and the Cursed Child, is sold out through 2017, while Rowling's tie-in book of the same name is the top seller of the year. By most accounts, the Harry Potter empire is worth north of $25 billion.

"If you're Tsujihara and you want to build franchises, who better to tap than J.K. Rowling?" says analyst Eric Handler of MKM Partners. "However, for the new series to succeed long term, you must have characters that are just as beloved as those in Harry Potter."

The original films featured kid wizards and the first three were rated PG, but Fantastic Beasts is PG-13 and likely to skew older. Still, Handler expects the movie to gross at least $600 million (it's currently tracking for a $70 million to $80 million domestic debut, and as much as $200 million worldwide as it opens around the globe).

There are few box-office "comps" for Fantastic Beasts, which follows Newt Scamander (Eddie Redmayne), an introverted wizard who accidentally unleashes a suitcase of magical creatures in New York. One is The Hobbit trilogy — New Line/Warner Bros.' follow-up to the Lord of the Rings series — that together grossed nearly $3 billion worldwide, due in part to the successful marketing campaign by Warner Bros.

One of those courted Potter fans is Kat Miller, 34, the marketing and creative director of MuggleNet.com, a Rowling fan site that, with The Leaky Cauldron and Snitch Seeker, are known as the "big three." Miller says Warners worked with her site extensively and that her readers are ready for more adult adventures (Miller has seen Fantastic Beasts three times, including at the New York world premiere).

"For the most part, people are excited these characters are the age they are," she says. "The majority of Potter fans are in their early to late 20s. People may be sad that it's not at Hogwarts, but I think they are more excited because they can see themselves in these characters at the age they currently are."

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KEEPING HARRY'S WORLD ALIVESince the final Potter film in 2011, author J.K. Rowling (and her Hollywood partners) have worked diligently to maintain the franchise.

APRIL 14, 2012 Pottermore, Rowling's website presenting new stories about characters from the original books, launches with 18,000 words of fresh tales.

NOV. 13, 2012Book of Spells, an augmented reality video game and companion to the Harry Potter series, is released on PlayStation 3.

NOV. 12, 2013Book of Potions, another augmented reality video game and follow-up to Book of Spells, is released on PlayStation 3.

JULY 15, 2014 The Wizarding World of Harry Potter attraction, similar to the land launched at Universal's Orlando park in 2010, opens at Universal Studios Japan. A Los Angeles attraction follows in 2016.

MARCH 8, 2016 Rowling releases History of Magic in North America on Pottermore, tracing magic in the Americas as a foundation for the arrival of Fantastic Beasts.

APRIL 26, 2016Rowling reveals that the screenplay for Fantastic Beasts will be released as a book on the day of the film's release, Nov. 18.

JULY 30, 2016Harry Potter and the Cursed Child, a two-part play (written by British playwright Jack Thorne) that follows an adult Harry Potter, opens in London. Tickets are sold out through 2017.

JULY 31, 2016Harry Potter and the Cursed Child's script book goes on sale. After three days, it becomes the fastest-selling book of the decade in the U.K. It's now the best-selling book of 2016 in the U.S.